Post-Stroke Cognitive Deficits
CVA · EP 10 · STROKE
Before You Listen
This episode covers the cognitive syndromes that determine independence after stroke even when motor function looks intact. A patient can walk the hall, lift a hand weight, and converse warmly, yet still be unable to live alone because they cannot attend to the left side of space, recognize a spouse by sight, sequence the steps of a meal, or distinguish their right hand from their left. You will leave with hemispatial neglect mechanism through prognosis, the three apraxias and their localizations, the agnosias including anosognosia and prosopagnosia, the four-feature Gerstmann tetrad, the visual-neglect-versus-hemianopia distinction, the formal executive function tests, the cognitive rehabilitation strategies, and the split between pseudobulbar affect and depression.
Prerequisites:
- Cerebral vascular territories: right middle cerebral artery (MCA), posterior cerebral artery (PCA), and anterior cerebral artery (ACA) supply
- Functional cortical anatomy of parietal, temporal, occipital, and frontal lobes
- The eight aphasia syndromes from CVA-09
Runtime: 1 hour 24 minutes
Vignette. A 65-year-old right-handed man is admitted to acute inpatient rehabilitation 5 days after a right middle cerebral artery (MCA) infarct. The nursing team reports he eats only the food on the right half of his hospital tray and is “hungry again” the moment a nurse rotates the tray 180 degrees. Occupational therapy notes that he dresses only the right side of his body and shaves only the right side of his face. When the physical therapist stands on his left and calls his name, he turns his head to the right searching for the source of the voice. On confrontation testing each visual field is intact in isolation; on simultaneous bilateral finger wiggling, he reports only the right-sided stimulus. He has a dense left hemiparesis but insists his left arm “works fine” and tries to stand and transfer alone. He has fallen twice.
Where is the lesion, what specific bedside finding distinguishes this from a homonymous hemianopia, what cognitive deficit explains his repeated unsafe transfer attempts, and what insight-independent therapy is best suited for this patient?
Section 1: Hemispatial Neglect, Mechanism, Localization, and the Hemispheric Asymmetry
Bottom line: hemispatial neglect is a failure to attend to the contralesional half of space despite intact primary sensory and motor pathways. It overwhelmingly follows right parietal stroke because the right hemisphere monitors both hemifields while the left monitors only the right, leaving no redundancy when the right hemisphere goes offline.
Hemispatial neglect is a failure to attend to, respond to, or orient toward stimuli on the side of space contralateral to a brain lesion when this failure cannot be explained by a primary sensory or motor deficit. The patient is not blind and is not paralyzed on the neglected side. Visual pathways from retina through optic nerve to occipital cortex may be entirely intact; the corticospinal tract on the affected side may be functional. The breakdown happens one synaptic step later, in the parietal attentional networks, where the brain does not allocate awareness to that half of space. This split between attentional failure and sensory failure is the foundation of every board question about neglect.
Neglect overwhelmingly follows right parietal lobe lesions in the non-dominant hemisphere. Left-sided neglect is far more common and far more severe than right-sided neglect. The asymmetry is not an accident: the left hemisphere attends primarily to the right side of space, while the right hemisphere attends to both sides. When the left hemisphere is damaged, the intact right hemisphere can compensate because it already monitors both hemifields. When the right hemisphere is damaged, the left hemisphere can only attend to the right and has no architectural capacity to cover the now-unmonitored left. The board examiner expects the candidate to articulate this redundancy.
Clinical manifestations are dramatic. The patient eats only the food on the right side of the tray and leaves the left untouched, not because they are not hungry but because food on the left does not register in conscious awareness. They begin reading sentences in the middle or skip left-sided words. They shave only the right side of the face, dress only the right arm, and collide with doorframes on the left when wheeling through halls. In severe cases the patient denies ownership of the left arm entirely. The patient who does not attend to the left half of space cannot safely transfer, ambulate, or operate a wheelchair without continuous supervision.
Neglect is not monolithic. Sensory (perceptual) neglect is the failure to perceive contralesional stimuli despite intact primary sensory pathways, and is the prototype that most board questions address. Motor neglect (intentional neglect, directional hypokinesia) is the failure to initiate or execute movements toward the affected hemispace; the limbs are not paralyzed, but the patient spontaneously fails to use the left side of the body. Personal neglect is neglect of the patient’s own body on the affected side. Spatial or extrapersonal neglect refers to neglect of the environment beyond the body and affects navigation, meal completion, and reading.
High Yield: Hemispatial Neglect Core Facts
- Definition: failure to attend to or respond to the contralesional half of space despite intact primary vision and intact motor pathways. Attentional failure, not sensory failure.
- Localization: right parietal lobe in the non-dominant hemisphere, classically in the right MCA territory.
- Asymmetry: left-sided neglect is far more common and more severe because the right hemisphere normally monitors both hemifields and the left hemisphere monitors only the right.
- Subtypes: sensory (perceptual), motor (intentional), personal (own body), spatial (extrapersonal). Boards most commonly test sensory and personal.
- Functional impact: independent negative predictor of functional outcome, longer rehab stay, higher fall risk, supervised discharge.
Board Trap: Neglect Is Not Stubbornness
A vignette describes a hemiplegic patient who “refuses” to look at the food on the left side of the tray and “ignores” the therapist who approaches from the left. The trap is to label this as poor motivation, depression, or noncompliance and recommend behavioral counseling. The correct answer is left hemispatial neglect from a right parietal stroke, and the appropriate intervention is visual scanning training, anchor cues, and prism adaptation. The patient cannot allocate attention to the left half of space, and the family must be educated explicitly that this is not stubbornness.
The left hemisphere acts as a fixed, rigid camera. Its lens only ever points to the right side of the room. The right hemisphere, however, operates as this wide-angle, constantly panning camera. It sweeps across and monitors both the left and the right sides of the room simultaneously.
— CVA-10 podcast, ~01:57